Biochemical Studies on Rice Bran Lipase

Abstract

Lipase extracted from defatted rice bran with calcium chloride solution was purified by ammonium sulfate precipitation, followed by successive column chromatographies on DEAE-cellulose, Sephadex G-75, CM-Sephadex C-50 in the presence of calcium ion. The specific activity of the purified enzyme was 4.7 units/mg protein and 480 times that of starting crude extract. The homogeneity of the enzyme protein was criticized by polyacrylamide gel disc electrophoresis and ultracentrifugation. The enzyme protein also behaved homogeneously in ampholine electrophoresis, indicating the isoelectric point of 8.56. The sedimentation coefficient of the enzyme was determined to be 2.97 S, and the molecular weight to be 40000 by Archibald's method. According to the measurement of optical rotatory dispersion of the enzyme, ORD constant, λc, Moffitt-Yang parameters, a0 and b0, were evaluated to be 239mμ, , -164 and -123, respectively.